Balrahd mentioned a lot of them. But think about this. If no defenders are around, then they can't heal through bleeding, they can't heal bleeding, the only place to heal disease is at the Village and that's if they make it there and if someone else isn't standing in the way, they can't recall/teleport away from danger and instead must walk everywhere, if they do thirst then they will then be fighting every mob in the way, thirst wears off after 2-6 ticks and then they are fatigued which means they're not regenerating hp/mp/mvs at a normal rate, a rager is easily predicable on where they will be and how they will get there, they can't control size or easily fly so most lagging moves work against them (except when thirsted), and so on.
It's so easy to take advantage of all of those things combined. Don't get me wrong, Villagers are very powerful at times. But you can control those instances to a great degree (and is partially why I deleted Firhindil - boredom).
If people would just play a Villager, just once, then they would realize all the shortcomings and difficulties of the cabal to then use against them with future characters.